1. Technical Field
The present invention relates to polarizers, methods of production thereof, projectors, liquid crystal devices, and electronic devices.
2. Related Art
Wire grid polarizers are known as a type of polarizer. The wire grid polarizer is configured to include a metallic grid overlaid on a transparent substrate in a pitch shorter than the wavelengths of the light used. Because the wire grid polarizer can be realized using only inorganic materials, deterioration due to photoirradiation occurs much less frequently than in polarizing plates that use organic materials. The wire grid polarizer has thus attracted interest as an effective device in liquid crystal projectors of ever increasing brightness.
Despite the excellent heat resistance of the wire grid polarizer, there is a demand for improved high-temperature reliability in the face of the increasing brightness of liquid crystal projectors.
JP-A-2005-37900 discloses that a polarizer having high contrast and excellent light use efficiency can be provided by lamination of a high-reflection grating layer and a high-absorption grating layer on a substrate. The photoabsorptive thin film disclosed in this publication uses high-melting-point materials such as tungsten, chromium, and molybdenum. However, oxidation resistance is poor, and the film is not suited for actual use in a high-temperature environment of 300° C. or higher.
JP-A-2009-186929 describes using carbon, carbides, oxides, sulfides, or nitrides as the preferred light use efficiency light absorbing material in terms of improving photoabsorbability. Specifically, a polarizer is disclosed in which aluminum oxide, iron oxide, nickel oxide, copper oxide, vanadium oxide, and chromium oxide are used as light absorbing materials. Metal oxides are among the materials having the highest oxidation resistance under a high-temperature environment. However, the attenuation coefficients k of the metal oxides described in the examples of JP-A-2009-186929 are very small in the visible range, and are not suited for practical applications. The attenuation coefficient k is the imaginary part of the complex refractive index N=n+ik. Other than oxides, the publication discloses carbides, sulfides, and nitrides as examples of the light absorbing material. However, a specific composition is not disclosed, and the publication is silent as to the optical absorption characteristics of these materials, and the oxidation resistance in a high-temperature environment.